The UN's top official for refugees today visited South Ossetia and called for people who had fled the conflict to be allowed home.

In the first visit to the region by a senior UN official, the high commissioner for refugees, Antonio Guterres, and the Russian foreign minister, Sergei Lavrov, agreed on the principle that all civilians should have the right to return home, a UNHCR statement said.

The UN estimates 158,000 people have been displaced since fighting broke out on August 7 over South Ossetia. About 80,000 people are being housed in more than 600 centres in and around the Georgian capital, Tbilisi. More than $11m (£5.9m) worth of aid has been flown into Georgia.

Humanitarian aid is getting to the beleaguered Georgian city of Gori, but the head of USAid, Henrietta Fore, said Russian military must open safe corridors to let aid workers and more supplies get through. She said workers managed to get into Gori yesterday to hand out supplies that had been brought in by her agency and the US military.

"The distribution of food and hygiene kits went well — that is just one day, but it's a step in the right direction," she said, but added that her own people must be let in to increase supplies and assess the situation.

In Georgia, Russian troops manned checkpoints and controlled traffic on major highways despite a promise to leave the country by today. As Russian military trucks roamed the roads and Russian military helicopters flew overhead, the withdrawal pledge by the Russian president, Dmitry Medvedev, seemed unlikely to be met.

"If they're leaving, it is at a snail's pace," said General John Craddock, commander of US European command, as he ended a two-day assessment trip in Georgia. "It is far too little and far too slow."

In Igoeti, a major checkpoint on the road from Tbilisi to Gori, Russian troops were allowing aid organisations and local traffic through. Red Cross vehicles, mine-clearing jeeps and trucks carrying peaches were seen heading into Gori.

Further west, near a base at the key Black Sea port of Poti, Russian troops were seen digging large trenches near a bridge that provides the only access to the city. Five trucks, several armoured personnel carriers and a helicopter were sitting nearby. Another Russian position was seen in a wooded area outside the city.

Alexander Lomaia, the head of Georgia's security council, said Russia's control of key roads aimed to "suffocate us economically" and "steer anger among the population, which can be channelled toward the government of this country".

While refugees from the fighting crammed Georgian schools and office buildings in and around the capital of Tbilisi, a scattering of people left in deserted villages were badly in need of basics.

"There is no bread, there is no food, no medicine. People are dying," said Nina Meladze, 45, in the village of Nadarbazevi, outside Gori. She stayed while others fled to Tbilisi because she could not leave elderly relatives behind. She said the village has been virtually abandoned since the war broke out.

"I cannot go on like this any more, I cry every day," she said.

The UN security council has remained deadlocked over Georgia, unable to agree on a resolution or statement on the crisis that erupted two weeks ago. Russia has put a draft resolution before the council endorsing a six-point peace plan brokered by Nicolas Sarkozy, the French president. But western countries say the Russian draft is unacceptable as it does not mention Georgia's territorial integrity and does not spell out where Russian forces will be deployed in future. Most importantly, the west says, Russia has made no substantial pullback.